Group 15 (Nitrogen family) and Group 16 (Oxygen family) - SS3 Chemistry Lesson Note
Group 15 and Group 16 are two adjacent groups in the p-block of the periodic table, consisting of elements known as the Nitrogen family and the Oxygen family, respectively. These groups contain some of the most abundant elements on Earth and have significant roles in various biological, industrial, and environmental processes. Let's explore the characteristics of Group 15 and Group 16 elements in detail:
Group 15 - Nitrogen Family:
1. Elements: The Nitrogen family includes five elements: nitrogen (N), phosphorus (P), arsenic (As), antimony (Sb), and bismuth (Bi). Nitrogen is a diatomic gas and makes up about 78% of the Earth's atmosphere.
2. Electron Configuration: Group 15 elements have five valence electrons in their outermost electron shell (ns2 np3). Nitrogen, being the first element in the group, exhibits some unique properties, such as a high ionisation energy and electronegativity.
3. Reactivity: Nitrogen is relatively inert and forms a stable triple bond with itself, making it less reactive than the other elements in the group. As you move down the group, the reactivity increases. Phosphorus can react with oxygen to form phosphorus oxides, and the reactivity further increases for arsenic, antimony, and bismuth.
4. Allotropes: Some Group 15 elements exhibit allotropy, existing in different forms with varying physical properties. For example, phosphorus has several allotropes, including white phosphorus (highly reactive and toxic) and red phosphorus (less reactive and used in safety matches).
5. Biological Importance:
● Nitrogen is a critical element in biological systems, forming essential components of proteins and nucleic acids (DNA and RNA).
● Phosphorus is vital in the form of phosphate groups in ATP (adenosine triphosphate), the primary energy carrier in cells.
Group 16 - Oxygen Family:
1. Elements: The Oxygen family consists of four elements: oxygen (O), sulphur (S), selenium (Se), and tellurium (Te). Oxygen is the most abundant element in the Earth's crust and the second most abundant element in the Earth's atmosphere.
2. Electron Configuration: Group 16 elements have six valence electrons in their outermost electron shell (ns2 np4). Oxygen is a highly electronegative element and readily forms covalent bonds with other elements.
3. Reactivity: Oxygen is highly reactive and participates in various chemical reactions, such as combustion and oxidation. As you move down the group, the reactivity decreases. Oxygen is highly reactive, sulphur is moderately reactive, selenium is less reactive, and tellurium is relatively unreactive.
4. Allotropes: Oxygen exhibits allotropy and exists primarily as O2 (dioxygen) in the atmosphere. Sulphur has many allotropes, including the cyclic S8 rings and long-chain polymeric sulphur.
5. Biological Importance:
● Oxygen is essential for respiration, where it serves as the final electron acceptor in cellular respiration.
● Sulphur is found in amino acids like cysteine and methionine, and it plays a role in protein folding and stability.
6. Industrial Applications:
● Sulphur and its compounds are used in the production of sulfuric acid, a crucial chemical in various industries.
Group 15 and Group 16 elements have diverse applications and play significant roles in both natural and human-made processes. Their unique properties and reactivities make them essential in various chemical, biological, and environmental contexts, contributing to the complexity and diversity of the natural world.